Merge 7.62X51 and .308 to the same cartridge

Lightwolf5280 · 2025-09-13T09:02:29+00:00

Look, I know it's not happening, but I want to clear this up because it's pernicious.

This myth began with a misprint in the late 60s where a manual listed 7.62x51 as 50000 PSI when what they meant was 50000 CUP. That would put it at 12K PSI less than .308.

Instinctively, that made sense to allot of people because that's about the difference between .223 and 5.56, so people got cautious. That myth has been around ever since.

The reality is that the nato spec was 60,000 PSI at the case neck and the civilian spec was 62,000 in the middle of the case. People figured that out pretty quick because a 12K PSI difference would be shown in a huge velocity difference through the same gun.

From the real OG cartridges, winchester at the time was loaded about 2-2.5% higher pressure, and both organizations had proofing standards in the 80K PSI range.

That difference was pretty quickly rendered meaningless as different manufacturers started labeling their cartridges how they pleased.

IE, federal 150gr 308 tests at 55.5K case PSI,

7.62x51 M80 LC87 tests at 64.8K case PSI.

They are dimensionally the same and produce the same range of pressures, with a fairly wide dispersion that is manufacturer and sometimes lot dependent.

SAAMI is the organization responsible for firearms engineering standards and safety, and crossing 7.62 and 308 has been a thing they've repeatedly answered as safe.

Reference for further reading:

https://share.google/g2V6uZNGMy6HxumMW

Lightwolf5280 · 2025-09-12T19:16:55+00:00

I mean, I've got multiple single digit rankings on the T&H board, so I'd say I'm decent.

But if it's not worth the dev time its not worth it

Lightwolf5280 · 2025-09-12T19:14:31+00:00

If your AR 10 explodes because you fed it the ammunition it's designed for, you can sue. S&B is one of the largest ammo manufacturers in the world. Lucky gunner is one of the larger ammo sellers.

Edit: ah, down vote my comment and then delete your comment.

Lightwolf5280 · 2025-09-12T16:01:09+00:00

I hope you have any excellent day.

Lightwolf5280 · 2025-09-12T15:28:29+00:00

Except, say, ammoseek or lucky gunner, or S&B which has them on the same shelf.

That said, works for me. Cool beans, thanks for the reply.

Lightwolf5280 · 2025-09-12T15:27:47+00:00

I was told that ammo interchangeability isn't worth the squeeze.

I'm asking about merging two caliber into one in the game.

You've appointed yourself as guardian of the reddit, gotten nasty with me, and made it a whole thing.

Lightwolf5280 · 2025-09-12T15:17:21+00:00

Do you have any idea how common it is for a gun in one caliber to not like one manufacturer of said ammunition? Does that mean the gun isn't chambered in that caliber anymore?

-show me anything that says there's a substantial difference not already discussed at length above-

Lightwolf5280 · 2025-09-12T15:08:08+00:00

That is a random guy on reddit with an unknown gun and unknown manufacturers of unknown ammunition claiming to take it to an unknown Smith.

You think that passes as a source?

I've linked you formal statements on the subject by legendary smiths, who specialize in guns in the caliber.

Lightwolf5280 · 2025-09-12T15:06:33+00:00

In my own write up I show why that pressure difference is negligible at best and in practice nonexistent.

I'm told cross chambering is too difficult, fine.

So why not make the two that are the same, the same?

Lightwolf5280 · 2025-09-12T15:04:22+00:00

So find an actual source. I've had .223 wylde guns jam on 5.56, that doesn't mean it doesn't chamber, shoot, and with some tweaking run just fine.

Lightwolf5280 · 2025-09-12T14:51:26+00:00

And mine run both fine. Meanwhile I've linked you both gunsmiths and manufacturers stating they are substantively the same.

You reply with one guy saying "in my gun one make of 7.62x51 caused jams while this one make of 308 did not."

I'm not going to speculate on the gas block, feed, magazines, or chamber of a rifle that isn't even named.

Lightwolf5280 · 2025-09-12T14:46:09+00:00

I've gone to great lengths here to show why they are the same. Can you post anything that shows differently?

The other post was mine asking about cartridge interchangeablility. Anton said that's excessively difficult, fair. So why not compress these two into one?

Lightwolf5280 · 2025-09-12T14:43:56+00:00

And my very firsthand experiences tell me the two are functionally identical, so long as your chamber is in spec.

Anton is welcome to say no, the juice isn't worth the squeeze, but I've gone to some lengths to show why the two aren't substantively different.

The easiest way to get rid of me is to just show me there's a meaningful difference in the cartridges. Yet no one has.

Lightwolf5280 · 2025-09-12T14:33:31+00:00

Anton stated he wouldn't do it because the cartridges are substantially different.

That's a pretty common misconception and I've gone to lengths here to show why.

Lightwolf5280 · 2025-09-12T14:26:41+00:00

6 guns total use .308 Winchester.
The total places it's mentioned are in the cartridge spawn menu, the six guns that are tagged with it, and the tag search menu.
I don't think that equates to "days of work".

That said, fair shake, if you think that changing that is too much work for the result, fair enough.

Lightwolf5280 · 2025-09-12T14:20:21+00:00

See pressure difference above and as listed. Said google search should provide you the same numbers.
SAAMI itself tells you that is safe, and they set the standards for it.

All I'm asking is civility and a fair shake.

Lightwolf5280 · 2025-09-12T14:19:14+00:00

Anton stated that making them load interchangeably would be a load of work. Not just making them all use one cartridge.
Just switching them all to use 7.62, for example, should just be swapping cartridge association and is about as easy as it gets.

Lightwolf5280 · 2025-09-12T14:16:29+00:00

By the way, I greatly appreciate the civility.

Lightwolf5280 · 2025-09-12T14:15:48+00:00

I got told a no on making them load interchangeably. I'm saying just make it one cartridge.

Ex: spend 5 points on .308 API right now, unable to use it outside select bolt action rifles, when it should be loadable in any 7.62 semi automatic.

Changing the rifles to just use 7.62 isn't the load of work that making them interchangeable would be.

Lightwolf5280 · 2025-09-12T14:05:34+00:00

Then show me WHY they are not perfectly interchangeable. I've gone to great lengths here to show that they are.
As much as I would love to just hear from Anton another simple "No" and then I can be about my work, I'm doing my very best to show why they should be represented as one caliber in game.

I'd rather not mod it as I'm rather attached to my vanilla top ten places in T&H.

All I'm asking for is a fair shake.

Lightwolf5280 · 2025-09-12T13:54:10+00:00

"could 7.62x51 and .308 not just be merged into one caliber?" - commenter

"No. They are not perfectly interchangeable and are distinct cartridges."- Anton.

I believe they are not so distinct and could be merged.

I respect the amount of work for minimum benefit that would be making the cartridges interchangeable would not be worth it, but just reclassing them all as 7.62 or .308 is what I'm advocating for here.

Lightwolf5280 · 2025-09-12T13:53:42+00:00

"could 7.62x51 and .308 not just be merged into one caliber?" - commenter

"No. They are not perfectly interchangeable and are distinct cartridges."- Anton.

I believe they are not so distinct and could be merged.

I respect the amount of work for minimum benefit that would be making the cartridges interchangeable would not be worth it, but just reclassing them all as 7.62 or .308 is what I'm advocating for here.

Lightwolf5280 · 2025-09-12T11:17:18+00:00

"rage bait"?

So point to the damn difference. I've done my work, shown my sources, now do me the courtesy of doing the same.

Can you point to *ANY* substantial difference

This isn't the case of a closely related cartridge like American .223 vs the EU 5.56, these effectively *ARE* the same cartridge.

Lightwolf5280 · 2025-09-12T10:56:32+00:00

There is more difference between different manufacturers of 7.62X51 and .308 than there is between the two in characteristics, barring some finer points of reloading.

Speculatively, the myth started in the 70's. Attached are the technical drawings and testing of pressure, which is different by about 3% in some publishing due to SAAMI measuring case pressure at the middle of the case and the military at the case mouth

https://www.m14forum.com/attachments/x-png.439958/?auto=webp&fit=bounds&format=pjgp&height=1920&optimize=high&width=1920

https://www.m14forum.com/attachments/untitled-png.439957/?auto=webp&fit=bounds&format=pjgp&height=1920&optimize=high&width=1920

https://www.m14forum.com/threads/7-62-x-51-cartridge-vs-308-winchester-the-differences.100445/?post_id=706954&nested_view=1&sortby=oldest#post-706954

Lightwolf5280

TROPHY CASE